“The Eternal spoke to Moses, saying: ‘Speak to the entire assembly of the Children of Israel and say to them: “Be holy, for I, the Lord your God, am holy”’” (Leviticus 19:1–2).
This week’s parashah begins with this principle of holiness. The concept seems simple. Yet, reaching that level—becoming “holy”—is the work of a lifetime, and there is always room for improvement and ascent.

The first question to ask when engaging in this path of spiritual greatness is: What is holiness?
The answer also seems simple. However, it is in fact a point of disagreement between two of the greatest Torah commentators: Rashi and Nachmanides (Ramban).

According to Rashi, the mitzvah of holiness means “keeping away from all that the Torah prohibits us from doing, particularly forbidden sexual relations.”
However, Nachmanides disagrees with Rashi’s interpretation, at least concerning this verse. Instead, he explains:
“Be holy”: In my opinion, this ‘separation’ is not about forbidden sexual relations, as Rashi says, but rather the kind of separation that the Torah speaks of when referring to spiritual elevation. For while the Torah warns us against forbidden sexual relations and unkosher foods, it permits marital intimacy, as well as [kosher] meat and wine. Thus, if someone has strong physical desires and behaves improperly with his own wife or with several women (since polygamy was once allowed), and eats kosher meat and drinks wine in a disgraceful way—because the Torah did not entirely forbid it—he would be a “naval bereshut haTorah”—a degenerate within the boundaries of what the Torah permits. Therefore, after the Torah clearly specifies what is prohibited, it goes on to tell us that we must also set limits on what is permitted.” (Nachmanides, Leviticus 19:2)

Thus, according to Nachmanides, “being holy” does not merely mean abstaining from what the Torah forbids; that is only the starting point for a Jew. Being holy means that even regarding what the Torah allows, one must exercise moderation. In Torah terms, this means using the physical world to help the body achieve spiritual goals. We do not eat simply to eat, and we do not indulge in other pleasures for their own sake. Rather, we use the physical world as a means of elevating ourselves—and, in doing so, we elevate the world itself. This, ultimately, is the Jewish people's primary role in creation.

The only issue is that if you consult the Minyan HaMitzvot—the list of the ten commandments at the start of Parashat Kedoshim, still in chapter 19—you’ll see that the first mitzvah listed is honoring one's parents. According to the Minyan HaMitzvot—and all commentators agree—the first mitzvah in this parashah is not “Be holy,” even though it sounds like one. Instead, it is based on the following verse, which commands us to honor our parents.
Does this mean that there is no mitzvah to be holy?
How can that be? Doesn’t the Torah say earlier:
“Moses went up to God, and the Lord called to him from the mountain: ‘Say to the house of Jacob and tell the children of Israel: You have seen what I did to Egypt, and how I carried you on eagles’ wings and brought you to Me. Now if you obey My voice and keep My covenant, you will be My special treasure among all the nations—for the whole earth is Mine. You will be to Me a kingdom of priests and a holy nation.’” (Exodus 19:3–6)
So holiness is our very purpose as the Jewish people.
Then why is such an important mitzvah not listed among the 613 mitzvot (aside from the fact that it would raise the count to 614)?

If there are any words that summarize the attitude every Jew should have towards life, it is this call in Leviticus: “Kedoshim Tihiyu”—“Be holy.”
So being holy is a mitzvah like any other—but with a difference. Most other mitzvot, such as eating kosher, putting up a mezuzah, or wearing tefillin, have clearly defined parameters. These mitzvot have clear guidelines—for instance, when meat is no longer kosher, when tefillin are invalid due to defects, or when the time for a mitzvah has passed (e.g., lighting Shabbat candles after sunset on Friday is no longer valid).

But in this case, for this Torah injunction “Kedoshim Tihiyu”—“Be holy”—we must ask:
What are the criteria for holiness? Are they tangible?

The concept of holiness is one that many nations have tried to grasp—with limited success and often disastrous consequences.
How many crusades and pogroms were launched in the name of “holiness”?
The issue may lie in the difference between the French (and other Western) translations and the original Hebrew term.

For example, the English word for “saint” is “holy,” derived from “halo,” as in the halos surrounding angels (cf. Halloween, short for All Hallows’ Eve—the eve of All Saints’ Day), and refers to those considered “saints” by the Anglican tradition.
But the Hebrew word “kadosh” comes from a root meaning “to separate.” This explains why kiddush—which separates Shabbat from the six weekdays—marks (after candle lighting) the start of Shabbat.
This shows that the kind of separation referred to here is not merely physical detachment from something “unholy,” as done by monks in other religions.

To me, from what I have learned, the first level of separation must begin in the mind: kedushah (holiness) stems from intellectual distinction.
The parashah of Kedoshim contains dozens of individual mitzvot.
The fact that a parashah entitled “Kedoshim”—referring to holy and moral behavior—deals with so many technical ritual details illustrates Judaism’s realistic view that the devil is always in the details.
Grand moral phrases and lofty expressions of sanctity are never enough to create genuine moral determination.
We know too many people whom we might consider “holy,” yet whose private behavior and carnal weaknesses betray their public displays of righteousness and morality.

The Torah takes great care to give the Children of Israel detailed instructions on how to achieve holy behavior and noble status.
Observing even the smallest commandments, being aware that Torah governs all aspects of life and behavior, and the willingness to obey God’s commands are the foundation of holiness for both the individual and the nation.

Restraint, self-discipline, trust in the Eternal, faithfulness to tradition, and the ability to discern the importance of small details—these are the elements that forge a holy Jewish personality.

The commandments related to greed and unjust gain, as well as those dealing with forbidden sexual relations, figure prominently in this parashah.

The rabbis of the Talmud warned us that most people, at some point in their lives, come to possess money or goods that do not truly belong to them—whether legally or morally.
Furthermore, a significant number of people (though described as a minority) commit sexual abuses and excesses.

It is therefore essential to place great emphasis on these two aspects of human behavior as we begin the task of creating holiness.
Hence, the Torah’s intricate details and subtleties on these issues. There are many ways to steal—not only material goods, but also stealing time, ideas (what we now call intellectual property), or even others’ emotions—and the Torah seeks to close all loopholes.

For instance, any false or misleading information given by a seller to a buyer is a violation of Torah law. Even giving a false impression to a customer is forbidden.

My father often said, “Honesty is built in the details.”
And details, by Jewish definition, are truly the fine details of the rituals that accompany each Torah commandment.
Beware: beautifying a mitzvah (hidur mitzvah) is not a baroque addition; it has meaning and reinforces the essence of the commandment.

The same applies to human sexuality, which can either be sanctified or degraded to an animalistic vulgarity, especially in a society where so much is disposable.
The details of the commandments regarding human behavior in this area are the rungs of the ladder that lead to holier conduct and nobler living.

Even actions and behaviors that are permitted—or even encouraged—by Torah law must include holy restraint and self-discipline.

Holiness means self-mastery over one’s desires and passions.
It is neither the abstinence nor the asceticism preached by other faiths and circles.
It is the ability to live a naturally pure and elevated life.

In summary, there is no higher goal or more certain formula for human satisfaction and happiness than “Kedoshim Tihiyu” – Be holy – in thought, attitude, behavior, and action.
Thus, the commandments described in our parashah help us achieve this beautiful kind of life.

“Being holy does not merely mean abstaining from what the Torah forbids; that is only the starting point for a Jew. Being holy means that even in what the Torah permits, one must act with moderation—which, in Torah terms, means using the physical world to help the body attain spiritual achievements. We do not eat just to eat, nor do we indulge in pleasures for their own sake. In essence, we use the physical world as a means to elevate ourselves—and in doing so, we elevate the physical world itself. This, ultimately, is the main role of the Jewish people in creation.”